1. Field of the Invention:
This invention relates generally to lasers, and more particularly to diode laser-pumped solid-state lasers.
2. Description of the Prior Art:
Laser diodes themselves are known as compact and highly efficient devices for generating laser beams. However, due to low energy storage capability, relatively low stability in output light frequency, relatively large light divergence, and so on, the laser diode has found only limited applications.
On the other hand, recent developments in pumping technology have led the attentions of researchers to the possibility of using the laser diode to pump another solid-state laser such as a neodymium-doped yttrium-aluminum-garnet laser (YAG laser) which has been formerly pumped by a linear flash lamp or by an arc lamp. Compared with the conventional pumping sources, the laser diode promises higher energy efficiency, lower heat generation (as required to produce high-quality laser beams) and longer life. The diode laser-pumped solid-state laser provides various potential applications which include coherent radar, global sensing from satellites, medical uses, micro-machining and miniature visible sources for digital optical storage.
For further understanding of the prior art, reference is now made to FIG. 2 of the accompanying drawings which show a typical diode laser-pumped solid-state laser.
As shown in FIG. 2, the prior art solid-state laser comprises a laser diode 101 for emitting divergent pumping light which is collected by a convergent lens 102. The pumping light thus collected enters axially into a laser rod such as a YAG rod 103 in which the active substance (Nd ion) is excited to generate a laser beam by stimulated emission. A part of the produced laser beam passes through a half mirror 104 as an output laser beam, whereas the remaining part is reflected back into the YAG rod for oscillation.
According to the above arrangement, the laser diode 101 is disposed coaxially of the YAG rod 103, so that only one such diode can be used as a pumping light source. Thus, there is a limitation on the achievable laser beam output.